mobile app or a web app, the answer is both.
You and your service should (ideally) be available and reachable everywhere. A mobile application and a website optimized for mobile device are essential.

However, I feel like you're simply using the wrong terminology
I think you might be referring to native vs hybrid app.
In this case, others are right there are ton a of articles that discuss&compare both. Bottom line is current assets, time&money and functionality.